Questions tagged [iterator]
An iterator is an object-oriented programming pattern which for the most part functions similarly to a pointer to an object inside a collection with the added ability to traverse through the collection in a defined manner, agnostic of the actual implementation or even object addresses in physical memory. Iterators may be further limited in particular traversal directions.
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Adding iterators to C++ sqlite wrapper class
I recently put up my C++ class to wrap the sqlite3 c library here:
Thin C++ wrapper for sqlite3 C library
One of the suggestions was rather than to specify a vector for arguments to functions instead ...
3
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1answer
84 views
Image (Const) Iterator using C++17
I am trying to learn how to correctly implement an iterator (and its corresponding const variant) using a single template, so I would appreciate any criticism to the following code. It's an forward ...
2
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1answer
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Implement a range behaviour in Python using iterators
I've been assigned the following Python homework:
Implement myrange that acts like range using iterators. Define a function ...
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0answers
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Rcpp sparse CSC matrix class
This is a sparse matrix (dgCMatrix) class that extends Rcpp.
WHAT: This class includes Rcpp::NumericVector and ...
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2answers
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Racing promises and consuming them in the order of their resolution time
The ideas are
When multiple async calls are made, to be able to start consuming from the first resolving one regardless in what order the promises are fired.
To construct a modern emitter of async ...
3
votes
3answers
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Throttled execution of an enumeration of Tasks
Example of use:
var users = await usernames.SelectTaskResults(GetUserDetails, 4);
where GetUserDetails(string username) is a ...
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0answers
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A C++ iterator that adds an extra layer of indirection
This iterator is designed with one purpose in mind. If before you had an iterator where you could do
int x = *it;
now you do
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4
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1answer
110 views
Forward List Implementation
NB: There's a bug with my iterator, apparently. I can't use const_iterator because I get some compiler errors. I know using const...
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1answer
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How to optimize this majority vote method
I have the following code to do a majority vote for data in a dataframe:
...
0
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1answer
66 views
Random Access Iterator Implementation
(This is the Non-const version, I have to implement the const one too).
Could someone please review this implementation? This is made for std::vector
I'm unsure whether I respected all requirements ...
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3answers
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Input Iterator implementation
I need some review on my implementation of input iterator. I am currently re-implementing std::vector, and need input_iterator for a specific constructor.
Any criticism is much appreciated! Thank you.
...
3
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1answer
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Cyclic generator with access to current local state and executes callback after each cycle
I'm working on a Python class that is a cyclic generator, like itertools.cycle, but it offers access to its current state and executes a callback after the ...
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1answer
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wrapper class for random access iterator to hide template method implementation from header file
I have a set of template functions that have itrator types as template parameters, so can be used with any kind of iterators. std::find can be a good example.
Also ...
4
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1answer
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Const wrapper for iterator
Edit: added clarification for why I want this, and updated the code since I don't have any answers yet
I have a C++11 array-like class which (can be) a wrapper around a random-access iterator. Index-...
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3answers
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Shorten dict comprehension with repeated operation
dc = {line.split('=')[0]: line.split('=')[1] for line in txt}
Below avoids duplication but is even longer:
...
4
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1answer
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Convert array of u32 to Vec<u8> in Rust
In Rust, I want to take an array of u32 values, convert each to four bytes in big endian, and concatenate them to yield a ...
6
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3answers
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Counting words from stored .md files
The following searches recursively for all the mark down files - i. ending with the extension .md - inside a folder. It then stores the text of the files in an ...
3
votes
1answer
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Get all routes that start with rt_
The code reads all my routes and return to my AJAX request the names of the routes without duplicates and just those that have the "rt_" prefix.
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3
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1answer
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Rust shortest way to find the maximum product of a fixed length substring
I'm trying to code in a Rust a function, that gives the maximum product of adjacent digits.
So given the string 123456789, with 3 adjacent digits, the maximum is <...
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1answer
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base64 iterators
Was a tiny bit bored reading authentication protocols.
Needed to clear the mind and read some base64 encode text.
So I implemented these iterators that will encode or decode base64 text.
Not sure ...
2
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0answers
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Async linked list to and from async iterable
I'm working on some stuff that works better with (immutable async) linked lists such as this:
...
3
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1answer
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Extending method chaining IEnumerable with Add..If
I'm trying to write an extension (method chaining) for playing around a bit.
What I made work is an extension to add an item to the list (what is pretty easy):
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2
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1answer
93 views
Generate binary image using coordinate vectors
I have a matrix M of size [n_rows, n_cols] and a list of x and ...
4
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0answers
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Deep map, Python
Goal: apply fn to every element of an arbitrarily nested iterable (tuple, list, dict, np.ndarray), including to iterables. Ex:
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3
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2answers
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Deep len, Python
Goal: find total number of elements in a nested iterable of arbitrary depth. My shot:
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2
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2answers
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0
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1answer
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Ensure queue is in ascending order
The program reads in a queue of integers and returns determines whether or not it is valid (ascending).
How can this code be improved?
I assume iterator include statement is unnecessary?
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2
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1answer
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Iterator-Pattern for an iterator that returns one objects that changes
I wrote an algorithm that returns all k-sized subgraphs of another given graph. Because I don't want to make the runtime of the next() call of the iterator depended on k, I don't want to return a new ...
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4answers
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Exercise: Design a Stack
Exercise: Design a Stack
A Stack is a data structure for storing a list of elements in a LIFO
(last in, first out) fashion. Design a class called Stack with three
methods.
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5
votes
1answer
162 views
`zip` operator to iterate on multiple container in a sign
I worked out a zip operator similar to Python's, because I didn't find one in std. It allows to use range-based ...
2
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1answer
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template iterable numeric range class with multiple min/max inclusion modes
Problem my code solves:
Lack of lightweight numeric range classes which can tell if arbitrary values lie inside them, supporting more than just simple exclusive max modes and integers, and that ...
3
votes
1answer
83 views
Splits up two comma separated items, if they exist
This method splits up two comma separated items, if they exist, and increments the amount if the are already in the list; otherwise add the item to the list
I want to know if this code can be ...
2
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1answer
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Compare length of iterator with as few `next` calls as possible. How can I deduplicate this code?
I'm writing a few simple functions that compare the length of an iterator to an integer, returning as early as possible. Right now I have:
...
0
votes
1answer
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c# QuadTree yielding properly [closed]
I have implemented a QuadTree of my own, and I'm afraid I didn't use yield properly when I query my tree, my fear is that I create O(HN) iterators.
Could you direct me how to better improve the ...
3
votes
0answers
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Populate a list with combinations of one- and two- object functions
I have a nested set of for loops which achieves the desired outcome, but I don't know if it is the most efficient / pythonic way of populating this list.
I would ...
9
votes
2answers
626 views
Manipulating list values in python
I wrote a function that I use to preprocess pandas dataframes before running them through a machine learning model. The function works perfectly, however I don't think it's the most pythonic way to ...
4
votes
1answer
66 views
Summation Over Lines in a File (Advent of Code 2018 Day 1)
Preface: I am learning Rust through the Advent of Code
The task is to read lines from a file, parse each as an integer, then provide a summation of all the numbers. My solution looks like this:
<...
3
votes
1answer
173 views
Iterate through Expression Tree
I'm trying to build an iterator (enumerator) that can select specific elements in an Expression tree by traversing the tree and deferring further iteration until ...
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2answers
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C++17 zip iterator compatible with std::sort
Here are ~100 lines of code implementing three classes (ZipRef, ZipIter, Zip) which should ...
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2answers
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Iterator for traversing a tree [v2]
this is an update of the implementation after I followed the feedback from Iterator for traversing a tree. After that I did changed quite a bit on the design and decided to ask for another round of ...
3
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1answer
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4
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1answer
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1
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1answer
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Bidirectional numeric (floating point) sequence iterator
I wanted a neat iterator that will always give me neat sequence of step spaced numbers. This is what I came up with, but I am a bit skeptical that I covered all ...
2
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0answers
878 views
Combining two nested for loops into one [closed]
Description
What this does is it takes a randomly generated 64x64 stack and checks
for overlap within the 64x64 array. Here is an example:
https://imgur.com/a/kkPRzhn. Each color is its own ...
2
votes
1answer
474 views
A simple priority queue in Java via linked list sorted by priority keys
Now I have this very simple priority queue. add and changePriority both run in \$\mathcal{O}(n)\$ and ...
1
vote
1answer
61 views
A GapHelper static class to create unique (non-existing) size restricted names
I am working with a 3th party library which has following interface defined for a processing task:
...
7
votes
1answer
261 views
Map unique raw words to a list of code words
Problem
Write a function that replaces the words in raw with the words in code_words such that the first occurrence of each ...
3
votes
1answer
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Aggregation on list forEach and maps improvals
I am using a function in a SpringBoot @RestController, with Lombok
This function is an intermediate result that permit me to do an aggregation between two classes.
This 2 classes are:
...
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1answer
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c++ python like range function to use in for loops
It's a simple range function that works like python range and it is only a syntactic sugar for the usual for loop
if we want to operate on numbers in the range from 1 to 10 (1 ... 9) we use this code ...
